JPH0978229A - Production of zinc-magnesium alloy plated steel sheet - Google Patents
Production of zinc-magnesium alloy plated steel sheetInfo
- Publication number
- JPH0978229A JPH0978229A JP25815495A JP25815495A JPH0978229A JP H0978229 A JPH0978229 A JP H0978229A JP 25815495 A JP25815495 A JP 25815495A JP 25815495 A JP25815495 A JP 25815495A JP H0978229 A JPH0978229 A JP H0978229A
- Authority
- JP
- Japan
- Prior art keywords
- layer
- steel sheet
- plating
- alloy
- vapor deposition
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
- C23C14/14—Metallic material, boron or silicon
- C23C14/16—Metallic material, boron or silicon on metallic substrates or on substrates of boron or silicon
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
- C23C14/56—Apparatus specially adapted for continuous coating; Arrangements for maintaining the vacuum, e.g. vacuum locks
- C23C14/562—Apparatus specially adapted for continuous coating; Arrangements for maintaining the vacuum, e.g. vacuum locks for coating elongated substrates
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C26/00—Coating not provided for in groups C23C2/00 - C23C24/00
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、耐食性、塗装性、加工
性、溶接性等に優れ、建材、家電、自動車等の構造材，
部品材料として好適なＺｎ−Ｍｇ合金めっき鋼板を製造
する方法に関する。BACKGROUND OF THE INVENTION The present invention has excellent corrosion resistance, paintability, workability, weldability, etc., and is a structural material for building materials, home appliances, automobiles, etc.
The present invention relates to a method for producing a Zn-Mg alloy plated steel sheet suitable as a component material.
【０００２】[0002]
【従来の技術】鋼板の耐食性を向上させるため、従来か
ら各種の表面処理が採用されている。なかでも、代表的
な表面処理方法であるＺｎめっきには、主として電気め
っき法、溶融めっき法が採用されている。耐食性の向上
に対する要求は年々高まる傾向にあり、これに伴って溶
融めっき法、電気めっき法において種々の改良が提案さ
れている。溶融めっき法でＺｎめっき鋼板の耐食性を向
上させようとすると、Ｚｎめっき層の付着量を増加させ
る、すなわち、めっき層を厚くすることが先ず考えられ
る。しかし、製造面からの制約により付着量には上限が
あり、付着量の増加によって耐食性の向上を図ることに
は限界がある。また、めっき層が厚くなると、めっき鋼
板をプレス形成するときにカジリ、フレーキング等の欠
陥を発生させる原因になりやすい。2. Description of the Related Art Various surface treatments have conventionally been employed to improve the corrosion resistance of steel sheets. Among them, an electroplating method and a hot-dip plating method are mainly used for Zn plating, which is a typical surface treatment method. The demand for improvement in corrosion resistance tends to increase year by year, and accordingly, various improvements in hot-dip plating and electroplating have been proposed. In order to improve the corrosion resistance of the Zn-plated steel sheet by the hot dip coating method, it is first considered to increase the amount of the Zn-plated layer attached, that is, to thicken the plated layer. However, there is an upper limit to the amount of adhesion due to restrictions from the viewpoint of manufacturing, and there is a limit to improving the corrosion resistance by increasing the amount of adhesion. Further, if the plating layer becomes thick, it tends to cause defects such as galling and flaking when the plated steel sheet is press-formed.
【０００３】一方、電気めっき法で同様に付着量を増加
させることも考えられる。しかし、電気めっき法で付着
量を増加させることは、めっき金属の折出に必要な電気
量を増加させ、めっき鋼板のコストを上昇させる原因と
なる。そこで、電気めっき法では、Ｚｎ−Ｎｉ合金めっ
き等のＺｎ合金めっきを施すことによって耐食性の向上
を図っている。しかし、Ｚｎ−Ｎｉ合金めっき層は、硬
質で脆く、成形加工の際めっき層に割れや欠け等の欠陥
を発生させやすい。このような欠陥がめっき層に発生す
ると、欠陥部を介して下地鋼が露出するため、めっき層
本来の性能が発揮されず、欠陥部を起点とした腐食が進
行する。以上のような背景から、高耐食性のＺｎ系合金
めっき鋼板を蒸着法で製造することが試みられている。
なかでも、Ｚｎ−Ｍｇ合金めっきは、優れた防食作用を
呈する材料として注目されている。たとえば、特開昭６
４−１７８５３号公報では、０．５〜４０重量％のＭｇ
を含むＺｎ−Ｍｇ合金めっき層を形成することを開示し
ている。また、Ｚｎ−Ｍｇ合金めっき層と下地鋼との間
にＺｎ，Ｎｉ，Ｃｕ，Ｍｇ，Ａｌ，Ｆｅ，Ｃｏ、Ｔｉ等
の中間層を介在させることによりめっき層の密着性及び
加工性が向上することが特開平２−１４１５８８号公報
で紹介されている。On the other hand, it is conceivable that the amount of adhesion is similarly increased by electroplating. However, increasing the amount of adhesion by the electroplating method increases the amount of electricity required for depositing the plated metal, and causes an increase in the cost of the plated steel sheet. Therefore, in the electroplating method, the corrosion resistance is improved by applying a Zn alloy plating such as a Zn-Ni alloy plating. However, the Zn—Ni alloy plating layer is hard and brittle, and tends to generate defects such as cracks and chips in the plating layer during molding. When such a defect occurs in the plating layer, the underlying steel is exposed through the defective portion, so that the original performance of the plating layer is not exhibited, and corrosion starting from the defective portion proceeds. From the above background, it has been attempted to manufacture a Zn-based alloy plated steel sheet having high corrosion resistance by a vapor deposition method.
Among them, Zn-Mg alloy plating is drawing attention as a material exhibiting an excellent anticorrosion effect. For example, JP-A-6
In JP-A-4-17853, 0.5 to 40% by weight of Mg is used.
It is disclosed that a Zn-Mg alloy plating layer containing is formed. Further, by interposing an intermediate layer of Zn, Ni, Cu, Mg, Al, Fe, Co, Ti or the like between the Zn-Mg alloy plating layer and the base steel, the adhesion and workability of the plating layer are improved. This is introduced in Japanese Patent Laid-Open No. 2-141588.
【０００４】本発明者等も、めっき層の中央部に高Ｍｇ
濃度層を形成し、その上下に低Ｍｇ濃度層を形成した積
層型構造のＺｎ−Ｍｇ合金めっき鋼板が、耐パウダリン
グ性、耐食性、スポット溶接性、密着性、耐変色性等で
優れた特性を発揮することを見出し、特願平６−２４３
３５８号で提案した。更に塗装後の塗膜の二次密着性と
高耐食性を両立させたものとして、最表層である低Ｍｇ
濃度層の付着量を規定すると共に、最表層である低Ｍｇ
濃度層の付着量に対する第１層の低Ｍｇ濃度層の付着量
比率を規定したＺｎ−Ｍｇ合金めっき鋼板を、特願平７
−６５０９６号として出願した。また、積層構造を有す
るＺｎ−Ｍｇ合金めっき鋼板の製造方法として、連続走
行する鋼板上にＺｎ，Ｍｇ、Ｚｎの順に独立して順次蒸
着めっきを行い、蒸着終了後のめっき鋼板が持つ熱によ
ってＺｎとＭｇの拡散反応を進行させることを特願平６
−５８６２４号，特願平６−２０５９２８号等で提案し
た。The present inventors have also found that the high Mg content in the center of the plating layer
A Zn-Mg alloy plated steel sheet having a laminated structure in which a concentration layer is formed and low Mg concentration layers are formed above and below the layer has excellent properties such as powdering resistance, corrosion resistance, spot weldability, adhesion, and discoloration resistance. To find out that the Japanese Patent Application No. 6-243
Proposed in No. 358. Furthermore, as the one having both secondary adhesion and high corrosion resistance of the coating film after coating, low Mg which is the outermost layer.
The amount of adhesion of the concentration layer is regulated, and the outermost layer of low Mg
A Zn-Mg alloy plated steel sheet in which the ratio of the amount of the low Mg concentration layer of the first layer to the amount of the concentration layer adhered is regulated is disclosed in Japanese Patent Application No.
-65096 was filed. In addition, as a method for manufacturing a Zn-Mg alloy plated steel sheet having a laminated structure, Zn, Mg, and Zn are sequentially vapor-deposited on a continuously-run steel sheet in this order, and Zn is heated by the heat of the plated steel sheet after vapor deposition. Patent application No. 6
-58624 and Japanese Patent Application No. 6-205928.
【０００５】[0005]
【発明が解決しようとする課題】Ｚｎ−Ｍｇ合金めっき
鋼板の製造に際し、蒸着終了後の鋼板の保有熱でＺｎと
Ｍｇの拡散を進行させることにより、積層構造のＺｎ−
Ｍｇ合金めっき層が形成される。しかし、蒸着終了後の
鋼板を冷却する冷却速度が小さいと、冷却中にもめっき
層内でＺｎとＭｇの拡散が進行する。その結果、最終的
にめっき層の断面構造が適正なものとならず、Ｚｎ−Ｍ
ｇ合金めっき鋼板が有する本来の耐食性、塗装性などの
特性が発揮されないことがある。本発明は、このような
問題を解消べく案出されたものであり、蒸着めっき後の
冷却条件を規定することによって、常に適正な断面構造
を有するＺｎ−Ｍｇ合金めっき鋼板を製造することを目
的とする。When a Zn-Mg alloy plated steel sheet is manufactured, the diffusion of Zn and Mg is promoted by the retained heat of the steel sheet after the completion of vapor deposition, so that the Zn-Mg alloy sheet having a laminated structure is formed.
A Mg alloy plating layer is formed. However, if the cooling rate for cooling the steel sheet after vapor deposition is low, Zn and Mg diffuse in the plating layer even during cooling. As a result, the cross-sectional structure of the plating layer was not finally proper, and Zn-M
The original properties of the g-alloy plated steel sheet, such as corrosion resistance and paintability, may not be exhibited. The present invention has been devised to solve such a problem, and an object of the present invention is to always manufacture a Zn-Mg alloy plated steel sheet having an appropriate cross-sectional structure by defining cooling conditions after vapor deposition plating. And
【０００６】[0006]
【課題を解決するための手段】本発明の製造方法は、そ
の目的を達成するため、連続して走行する鋼板を真空室
に導入し、Ｚｎ，Ｍｇ，Ｚｎの順に蒸着めっきした後、
蒸着めっき完了直後の鋼板温度が３７０℃以下、蒸着め
っき完了から１０秒後の鋼板温度が３４０℃以下、２０
秒後の鋼板温度が３２０℃以下、４０秒後の鋼板温度が
３００℃以下になる冷却条件下で、めっき後の鋼板を冷
却することを特徴とする。In order to achieve the object, the manufacturing method of the present invention introduces a continuously running steel plate into a vacuum chamber, deposits Zn, Mg and Zn in order and then
Steel plate temperature immediately after completion of vapor deposition plating is 370 ° C. or lower, steel plate temperature 10 seconds after completion of vapor deposition plating is 340 ° C. or lower, 20
The steel sheet after plating is cooled under cooling conditions such that the steel sheet temperature after 3 seconds is 320 ° C. or less and the steel sheet temperature after 40 seconds is 300 ° C. or less.
【０００７】[0007]
【作用】適正な断面構造のＺｎ−Ｍｇ合金めっき鋼板と
は、本発明者等の調査・研究によるとき、３層（図１）
又は５層（図２）の積層構造をもつＺｎ−Ｍｇ合金層が
鋼板の表面に順次積層されたものである。このような積
層構造により、Ｚｎ−Ｍｇ合金めっき本来の特性が十分
発揮され、耐食性、塗装密着性、加工性、溶接性などの
諸特性が総合的に優れたものとなる。図１の３層構造で
は、Ｍｇ濃度０．５重量％以下のＺｎ−Ｍｇ合金層（第
１層），Ｍｇ濃度７重量％以上のＺｎ−Ｍｇ合金層（第
２層），そして最表層にＭｇ濃度０．５重量％以下のＺ
ｎ−Ｍｇ合金層（第３層）が鋼板上に順次積層された断
面構造のものを適正とする。[Function] A Zn-Mg alloy plated steel sheet having an appropriate cross-sectional structure means three layers (Fig. 1) according to the investigation and research by the present inventors.
Alternatively, a Zn—Mg alloy layer having a laminated structure of 5 layers (FIG. 2) is sequentially laminated on the surface of the steel sheet. With such a laminated structure, the original characteristics of the Zn-Mg alloy plating are sufficiently exhibited, and various characteristics such as corrosion resistance, coating adhesion, workability, and weldability become comprehensively excellent. In the three-layer structure of FIG. 1, a Zn-Mg alloy layer having a Mg concentration of 0.5 wt% or less (first layer), a Zn-Mg alloy layer having a Mg concentration of 7 wt% or more (second layer), and an outermost layer are formed. Z with a Mg concentration of 0.5% by weight or less
An n-Mg alloy layer (third layer) having a cross-sectional structure sequentially laminated on a steel plate is appropriate.
【０００８】図２の５層構造では、Ｍｇ濃度０．５重量
％以下のＺｎ−Ｍｇ合金層（第１層），Ｍｇ濃度２〜７
重量％のＺｎ−Ｍｇ合金層（第２層），Ｍｇ濃度７重量
％以上のＺｎ−Ｍｇ合金層（第３層），Ｍｇ濃度２〜７
重量％のＺｎ−Ｍｇ合金層（第４層），そして最表層に
Ｍｇ濃度０．５重量％以下のＺｎ−Ｍｇ合金層（第５
層）が鋼板上に順次積層された断面構造のものを適正と
する。３層構造又は５層構造の何れの場合でも、最表層
のＺｎ−Ｍｇ合金層は、塗装を施した場合のめっき層と
塗膜との間の密着強度を確保するために、付着量を０．
３ｇ／ｍ2 以上とすることが好ましい。Ｍｇ濃度が７重
量％以上の層は、それ自体の耐食性が高く、めっき層自
体の腐食寿命を長くする。また、Ｍｇ濃度が高い層から
溶け出したＭｇは、防食性に優れたＺｎの腐食生成物で
あるＺｎＣｌ2 ・４Ｚｎ（ＯＨ）2 やＺｎ（ＯＨ）2 の
生成を促進するので、更に耐食性が向上する。しかし、
Ｍｇ濃度７重量％以上の層が最表層として露出している
と、めっき鋼板の表面に塗料を塗布した場合に塗膜二次
密着性が得られないことがある。In the five-layer structure of FIG. 2, a Zn-Mg alloy layer (first layer) having a Mg concentration of 0.5% by weight or less, and a Mg concentration of 2 to 7 are used.
Wt% Zn-Mg alloy layer (second layer), Mg concentration 7 wt% or more Zn-Mg alloy layer (third layer), Mg concentration 2 to 7
Wt% Zn-Mg alloy layer (fourth layer), and the outermost layer has a Mg concentration of 0.5 wt% or less Zn-Mg alloy layer (fifth layer).
A layer having a cross-sectional structure in which layers are sequentially laminated on a steel plate is appropriate. In either case of the three-layer structure or the five-layer structure, the Zn-Mg alloy layer of the outermost layer has an adhesion amount of 0 in order to secure the adhesion strength between the plating layer and the coating film when the coating is applied. ．
It is preferably 3 g / m 2 or more. A layer having a Mg concentration of 7% by weight or more has high corrosion resistance of itself, and prolongs the corrosion life of the plating layer itself. Further, since Mg dissolved out from the layer having a high Mg concentration promotes the formation of ZnCl 2 .4Zn (OH) 2 and Zn (OH) 2 which are corrosion products of Zn having excellent corrosion resistance, the corrosion resistance is further improved. improves. But,
When a layer having a Mg concentration of 7% by weight or more is exposed as the outermost layer, the coating film secondary adhesion may not be obtained when a coating material is applied to the surface of the plated steel sheet.
【０００９】具体的には、Ｍｇ濃度の高いＺｎ−Ｍｇ合
金層は、塗料との界面に水や水蒸気の侵入があると塗膜
の密着強度が大幅に低下し、結果として塗装後の耐水二
次密着性が得られない。この問題を解消するためには、
めっき層の最表層として、Ｍｇ濃度０．５重量％以下の
Ｚｎ−Ｍｇ合金層を０．３ｇ／ｍ2 以上の付着量で形成
することが有効な手段である。また、めっき層の表層と
化成処理層又は塗料との間で反応層が生成する場合、Ｍ
ｇ濃度０．５重量％以下のＺｎ−Ｍｇ合金層が全て反応
層となってしまうことがあり、その場合にも耐水二次密
着性が低下する。以上のような理由から、最表層には、
Ｍｇ濃度０．５重量％以下のＺｎ−Ｍｇ合金層を０．３
ｇ／ｍ2 以上の付着量で形成することが好ましい。最表
層にあるＭｇ濃度０．５重量％以下のＺｎ−Ｍｇ合金層
は、腐食に対する溶解速度が大きいことから犠牲防食作
用を呈する。すなわち、めっき鋼板に疵付き部等があっ
た場合、その部位からの赤錆発生が防止される。Ｚｎ−
Ｍｇ合金層により犠牲防食作用は、特に初期の赤錆発生
防止に有効である。Specifically, in a Zn--Mg alloy layer having a high Mg concentration, the adhesion strength of the coating film is significantly reduced when water or water vapor enters the interface with the coating material, and as a result, the water resistance after coating is increased. Secondary adhesion cannot be obtained. To solve this problem,
As an outermost layer of the plating layer, it is an effective means to form a Zn—Mg alloy layer having a Mg concentration of 0.5% by weight or less with an adhesion amount of 0.3 g / m 2 or more. Further, when a reaction layer is formed between the surface layer of the plating layer and the chemical conversion treatment layer or the paint, M
All Zn-Mg alloy layers having a g concentration of 0.5% by weight or less may become a reaction layer, and in that case also, the water-resistant secondary adhesiveness decreases. For the above reasons, the outermost layer is
A Zn-Mg alloy layer having a Mg concentration of 0.5% by weight or less is 0.3
It is preferable to form with an adhesion amount of g / m 2 or more. The Zn-Mg alloy layer in the outermost layer having a Mg concentration of 0.5% by weight or less exhibits a sacrificial anticorrosion action because it has a high dissolution rate against corrosion. That is, when the plated steel sheet has a flawed portion or the like, the generation of red rust from that portion is prevented. Zn-
The sacrificial anticorrosive action by the Mg alloy layer is particularly effective for preventing the initial generation of red rust.
【００１０】最表層のＺｎ−Ｍｇ合金層は、スポット溶
接性を向上させる効果もある。すなわち、この合金層が
最表層としてあることにより、スポット溶接の電極は、
Ｍｇ濃度０．５重量％以下の層と接し、高Ｍｇ濃度の層
が直接電極と接触する場合に比較して電極へのＭｇ拡散
を抑制し、電極寿命を長くする。更に、表面に高濃度の
Ｍｇが存在すると、めっき鋼板表面に自然に生成するＺ
ｎの酸化物や水酸化物が不飽和になり易く、黒変色が生
じ易い。この点、最表層をＭｇ濃度０．５重量％以下の
Ｚｎ−Ｍｇ合金層とするとき、表面のＭｇ濃度が低く抑
えられ、黒変色も防止される。Ｍｇ濃度７重量％以上の
層と下地鋼との間には、めっき鋼板の成形性を確保する
ため、第１層としてＭｇ濃度０．５重量％以下のＺｎ−
Ｍｇ合金層を形成することが望ましい。この第１層は、
延性を持っているため、めっき鋼板がプレス成形等の加
工により変形を受ける場合に、下地鋼と高Ｍｇ濃度層と
の間で変形量の差を吸収する作用を呈する。その結果、
パウダリングの発生が防止され、Ｚｎ−Ｍｇ合金めっき
鋼板の成形性が向上する。The outermost Zn-Mg alloy layer also has the effect of improving spot weldability. That is, by this alloy layer as the outermost layer, the electrode of spot welding,
The contact with a layer having a Mg concentration of 0.5% by weight or less suppresses the diffusion of Mg into the electrode and prolongs the life of the electrode, as compared with the case where the layer having a high Mg concentration directly contacts the electrode. Furthermore, when a high concentration of Mg is present on the surface, Z that naturally forms on the surface of the plated steel sheet
The oxide or hydroxide of n is likely to be unsaturated, and black discoloration is likely to occur. In this respect, when the outermost layer is a Zn-Mg alloy layer having a Mg concentration of 0.5% by weight or less, the Mg concentration on the surface is suppressed to be low, and black discoloration is also prevented. Between the layer having a Mg concentration of 7% by weight or more and the base steel, Zn-containing a Mg concentration of 0.5% by weight or less as a first layer in order to secure the formability of the plated steel sheet.
It is desirable to form a Mg alloy layer. This first layer is
Since it has ductility, it exhibits an effect of absorbing the difference in deformation amount between the base steel and the high Mg concentration layer when the plated steel sheet is deformed by processing such as press forming. as a result,
Generation of powdering is prevented, and the formability of the Zn-Mg alloy plated steel sheet is improved.
【００１１】更に、第１層のＭｇ濃度０．５重量％以下
のＺｎ−Ｍｇ合金層と下地鋼との間には、めっき層の密
着性を確保するためにＺｎ−Ｆｅ合金層又はＺｎ−Ｆｅ
−Ｍｇ合金層を形成することが好ましい。蒸着法によっ
て鋼板上にＺｎ−Ｍｇ合金めっきを形成しようとする場
合、蒸着雰囲気中にガス成分として存在するＯ2 やＨ2
Ｏによって鋼板表面が酸化されると、めっき密着性が低
下することがある。また、鋼板表面を活性化した後、直
ちに蒸着めっきが行われないので、その間に表面が汚染
されて密着性が低下する虞れもある。このようなめっき
密着性の低下は、第１層と下地鋼との界面にＺｎ−Ｆｅ
合金層又はＺｎ−Ｆｅ−Ｍｇ合金層を形成することによ
り防止される。ただし、Ｚｎ−Ｆｅ合金層又はＺｎ−Ｆ
ｅ−Ｍｇ合金層の厚みは、加工成形時にパウダリングが
発生しないように０．５μｍ以下に抑えることが有効で
ある。このような理由から、図１に示した３層構造をも
つＺｎ−Ｍｇ合金めっき鋼板は、耐食性，加工性，塗膜
密着性等において優れた特性を呈する。更に高耐食性が
要求される場合には、図２に示す５層構造にすることが
好ましい。５層構造は、３層構造と比較して、第２層及
び第４層にそれぞれＭｇ濃度２〜７重量％のＺｎＭｇ合
金層を設けたものである。Further, between the Zn-Mg alloy layer having a Mg concentration of 0.5% by weight or less in the first layer and the base steel, a Zn-Fe alloy layer or a Zn-Fe alloy layer or a Zn-Fe alloy layer is provided in order to secure adhesion of the plating layer. Fe
-It is preferable to form a Mg alloy layer. When forming a Zn-Mg alloy plating on a steel sheet by a vapor deposition method, O 2 and H 2 existing as gas components in the vapor deposition atmosphere
If the surface of the steel sheet is oxidized by O, the plating adhesion may be reduced. Further, since vapor deposition plating is not carried out immediately after activating the surface of the steel sheet, there is a possibility that the surface is contaminated during that time and the adhesion is lowered. Such a decrease in plating adhesion is caused by Zn-Fe at the interface between the first layer and the base steel.
It is prevented by forming an alloy layer or a Zn-Fe-Mg alloy layer. However, Zn-Fe alloy layer or Zn-F
It is effective to suppress the thickness of the e-Mg alloy layer to 0.5 μm or less so that powdering does not occur during processing and molding. For these reasons, the Zn-Mg alloy plated steel sheet having the three-layer structure shown in FIG. 1 exhibits excellent characteristics in corrosion resistance, workability, coating adhesion, and the like. When higher corrosion resistance is required, it is preferable to use the five-layer structure shown in FIG. The five-layer structure is different from the three-layer structure in that a ZnMg alloy layer having a Mg concentration of 2 to 7 wt% is provided in each of the second layer and the fourth layer.
【００１２】このような積層構造をもつＺｎ−Ｍｇ合金
めっき鋼板は、蒸着めっき完了後にめっき鋼板が持つ熱
によってＺｎとＭｇとを拡散させることにより製造でき
る。しかし、めっき後の鋼板を冷却する際に、冷却が遅
く鋼板が高い温度に保持される時間が長いと、冷却中に
もＺｎとＭｇの拡散が過度に進行し、最終的には適正な
積層構造のＺｎ−Ｍｇ合金めっきとならないことがあ
る。たとえば、拡散の進行によっては、３層又は５層の
積層構造にならず、図４〜６に示すようにＭｇがめっき
層全体にわたって拡散した１層めっき構造となる。しか
も、下地鋼からＦｅがめっき層中に拡散し、厚さ０．５
μｍ以上に成長したＺｎ−Ｆｅ合金層が存在する場合も
ある（図５，６）。厚いＺｎ−Ｆｅ合金層は、めっき鋼
板を加工した場合にパウダリングと呼ばれるめっき層の
剥離現象を起こし易い。The Zn-Mg alloy plated steel sheet having such a laminated structure can be manufactured by diffusing Zn and Mg by the heat of the plated steel sheet after vapor deposition plating is completed. However, when cooling the steel sheet after plating, if the cooling is slow and the steel sheet is kept at a high temperature for a long time, the diffusion of Zn and Mg excessively progresses during the cooling, and finally the proper lamination is achieved. The structure may not be Zn-Mg alloy plating. For example, depending on the progress of diffusion, a three-layer or five-layer laminated structure is not formed, but a single-layer plated structure in which Mg is diffused over the entire plated layer as shown in FIGS. Moreover, Fe diffuses from the base steel into the plating layer, and the thickness is 0.5
There may be a Zn—Fe alloy layer grown to a thickness of μm or more (FIGS. 5 and 6). A thick Zn-Fe alloy layer is apt to cause a peeling phenomenon of the plating layer called powdering when the plated steel sheet is processed.
【００１３】本発明では、図１又は図２に示した積層構
造を得るため、蒸着めっき完了直後及び蒸着めっき完了
後の経過時間に応じた鋼板温度を管理している。すなわ
ち、蒸着めっき完了直後の鋼板温度が３７０℃以下、蒸
着めっき完了から１０秒後の鋼板温度が３４０℃以下、
２０秒後の鋼板温度が３２０℃以下、４０秒後の鋼板温
度が３００℃以下となるように冷却する。この冷却条件
は、本発明者等による多数の実験結果から見出されたも
のであり、Ｍｇ及びＺｎの拡散を適正化し、図１又は図
２の積層構造をもつＺｎ−Ｍｇ合金めっき層を安定的に
形成する。蒸着めっき完了直後の鋼板温度が３７０℃を
超えると、めっき層と下地鋼との界面に生成するＺｎ−
Ｆｅ合金層又はＺｎ−Ｆｅ−Ｍｇ合金層が厚くなり、
０．５μｍを超えるので好ましくない。また、蒸着完了
から１０秒後に３４０℃以下，２０秒後に３２０℃以
下，４０秒後に３００℃以下となる条件の何れかでも満
足されないと、Ｚｎ−Ｍｇ合金めっき鋼板の断面構造
は、適正な３層又は５層にならず、図４〜６の１層構造
になりやすい。In the present invention, in order to obtain the laminated structure shown in FIG. 1 or 2, the temperature of the steel sheet is controlled immediately after completion of vapor deposition plating and according to the elapsed time after completion of vapor deposition plating. That is, the steel plate temperature immediately after completion of vapor deposition plating is 370 ° C. or lower, and the steel plate temperature 10 seconds after completion of vapor deposition plating is 340 ° C. or lower,
It cools so that the steel plate temperature after 20 seconds may be 320 ° C. or lower and the steel plate temperature after 40 seconds may be 300 ° C. or lower. This cooling condition has been found out from a large number of experimental results by the present inventors, and optimized the diffusion of Mg and Zn to stabilize the Zn-Mg alloy plating layer having the laminated structure of FIG. 1 or 2. Form. When the temperature of the steel sheet immediately after the completion of vapor deposition plating exceeds 370 ° C., Zn− formed at the interface between the plating layer and the base steel.
The Fe alloy layer or the Zn-Fe-Mg alloy layer becomes thicker,
Since it exceeds 0.5 μm, it is not preferable. Further, if any of the conditions of 340 ° C. or less 10 seconds after the completion of vapor deposition, 320 ° C. or less after 20 seconds, and 300 ° C. or less after 40 seconds is not satisfied, the sectional structure of the Zn—Mg alloy plated steel sheet has an appropriate 3 The number of layers is not five or five, and the one-layer structure shown in FIGS.
【００１４】本発明に従った冷却条件は、たとえば図２
に示す設備構成でＺｎ−Ｍｇ合金めっき鋼板を製造する
とき、次のように管理される。めっき原板１０は、ペイ
オフリール１１から巻き戻され、無酸化炉２０及び還元
焼鈍炉２５で表面活性化及び焼鈍された後、鋼板温度制
御装置２６を経て真空室３０に導かれる。真空室３０
は、入側真空シール部３１及び出側真空シール部３２を
備えた気密構造をもち、適宜の真空ポンプにより１Ｐａ
程度の減圧雰囲気に維持される。真空室３０の内部に
は、めっき原板１０の搬送方向に沿って第１Ｚｎ蒸着室
３３，Ｍｇ蒸着室３４及び第２Ｚｎ蒸着室３５が順次配
置されている。真空室３０に導入されためっき原板１０
は、第１Ｚｎ蒸着室３３で先ずＺｎ蒸着され、次いでＭ
ｇ蒸着室３４でＭｇ蒸着され、更に第２Ｚｎ蒸着室３５
でＺｎ蒸着される。蒸着めっきは、必要に応じてめっき
原板１０の片面又は両面に施される。The cooling conditions according to the present invention are shown in FIG.
When a Zn-Mg alloy plated steel sheet is manufactured with the equipment configuration shown in (1), it is managed as follows. The original plating plate 10 is rewound from the payoff reel 11, surface-activated and annealed in the non-oxidizing furnace 20 and the reduction annealing furnace 25, and then introduced into the vacuum chamber 30 via the steel plate temperature control device 26. Vacuum chamber 30
Has an airtight structure including an inlet side vacuum seal portion 31 and an outlet side vacuum seal portion 32, and is 1 Pa by an appropriate vacuum pump.
It is maintained in a reduced pressure atmosphere. Inside the vacuum chamber 30, a first Zn vapor deposition chamber 33, a Mg vapor deposition chamber 34, and a second Zn vapor deposition chamber 35 are sequentially arranged along the transport direction of the original plating plate 10. The original plating plate 10 introduced into the vacuum chamber 30
Is first deposited by Zn in the first Zn deposition chamber 33, and then M
Mg is vapor-deposited in the g-vapor deposition chamber 34, and the second Zn vapor-deposition chamber 35 is further deposited.
Zn is vapor-deposited. The vapor deposition plating is performed on one side or both sides of the original plating plate 10 as necessary.
【００１５】蒸着後のめっき鋼板１０は、出側真空シー
ル部３２を経て真空室３０から送り出され、一次冷却装
置４０及び二次冷却装置４５を通り、最終的にめっき鋼
帯１５として巻取りリール１６に巻き取られる。めっき
鋼帯１５は、一次冷却装置４０において窒素ガス吹付け
により冷却され、二次冷却装置４５において空気吹き付
けにより冷却される。冷却装置４０，４５の冷却能は、
吹き付ける窒素ガスや空気の温度及び流量によって調整
される。この蒸着めっきラインにおいて、第２Ｚｎ蒸着
室３５の直後に温度計５１を、真空室３０の出側に温度
計５２を、一次冷却装置４０の出側に温度計５３を、二
次冷却装置４５の出側に温度計５４を、巻取りリール１
６の上流側にある後処理装置（図示せず）の入側に温度
計５５をそれぞれ設けている。温度計５１〜５５として
は、たとえば放射温度計が使用される。温度計５１で測
定される温度は、蒸着めっき完了直後の鋼板温度であ
る。The vapor-deposited plated steel sheet 10 is sent out from the vacuum chamber 30 through the outlet side vacuum seal portion 32, passes through the primary cooling device 40 and the secondary cooling device 45, and finally as a plated steel strip 15 as a take-up reel. It is wound up in 16. The galvanized steel strip 15 is cooled in the primary cooling device 40 by blowing nitrogen gas, and is cooled in the secondary cooling device 45 by blowing air. The cooling capacity of the cooling devices 40 and 45 is
It is adjusted by the temperature and flow rate of the sprayed nitrogen gas or air. In this vapor deposition plating line, a thermometer 51 is provided immediately after the second Zn vapor deposition chamber 35, a thermometer 52 is provided at the outlet side of the vacuum chamber 30, a thermometer 53 is provided at the outlet side of the primary cooling device 40, and a secondary cooling device 45 is provided. A thermometer 54 on the outlet side and a take-up reel 1
Thermometers 55 are provided on the inlet sides of the post-treatment devices (not shown) on the upstream side of 6. Radiation thermometers are used as the thermometers 51 to 55, for example. The temperature measured by the thermometer 51 is the steel plate temperature immediately after the completion of vapor deposition plating.
【００１６】また、通板速度が６０ｍ／分の場合、温度
計５２で蒸着めっき完了から１０秒経過した時点の鋼板
温度，温度計５３で２０秒経過した時点の鋼板温度，温
度計５４で４０秒経過した時点の鋼板温度が測定され
る。また、通板速度が１２０ｍ／分の場合、蒸着めっき
完了から４０秒経過した時点の鋼板温度が温度計５５で
測定されるように、温度計５５の設置箇所を定めてい
る。温度計５１，５２の測定値に基づき、蒸着完了直後
の鋼板温度が３７０℃以下となるように鋼板温度制御装
置２６を制御し、蒸着前の鋼板温度を制御する。また、
温度計５５の測定値に基づき、一次冷却装置４０及び二
次冷却装置４１の冷却能力が制御される。このようにし
て、蒸着めっき完了直後の鋼板温度が３７０℃以下に、
蒸着めっき完了から１０秒経過した時点の鋼板温度が３
４０℃以下に、蒸着めっき完了から２０秒経過した時点
の鋼板温度が３２０℃以下に、蒸着めっき完了から４０
秒経過した時点の鋼板温度が３００℃以下に制御され
る。Further, when the sheet passing speed is 60 m / min, the temperature of the steel plate at 10 seconds after the completion of the vapor deposition plating by the thermometer 52, the temperature of the steel plate at 20 seconds by the thermometer 53, and the temperature at the thermometer 54 of 40 The steel plate temperature at the time when a second has elapsed is measured. Further, when the plate passing speed is 120 m / min, the installation location of the thermometer 55 is determined so that the steel plate temperature at the time of 40 seconds after the completion of vapor deposition plating is measured by the thermometer 55. Based on the measured values of the thermometers 51 and 52, the steel plate temperature control device 26 is controlled so that the steel plate temperature immediately after the completion of vapor deposition becomes 370 ° C. or less, and the steel plate temperature before vapor deposition is controlled. Also,
Based on the measurement value of the thermometer 55, the cooling capacities of the primary cooling device 40 and the secondary cooling device 41 are controlled. In this way, the steel plate temperature immediately after the completion of vapor deposition plating is 370 ° C. or less,
Steel plate temperature is 3 at 10 seconds after vapor deposition is completed
The temperature of the steel plate at 40 ° C. or lower is 20 ° C. after completion of the vapor deposition plating, and the steel plate temperature is 320 ° C. or lower at 40 ° C. from the completion of vapor deposition plating.
The steel plate temperature at the time when a second has elapsed is controlled to 300 ° C. or lower.
【００１７】[0017]
【実施例】表１に示した成分をもつ板厚０．５ｍｍ，板
幅７００ｍｍの未焼鈍冷延鋼板をめっき原板として使用
し、図３に示す蒸着めっき装置によりＺｎ−Ｍｇ合金め
っき鋼板を製造した。めっき付着量を片面あたり２０〜
５０ｇ／ｍ2 ，Ｍｇ濃度を３重量％に設定した。たとえ
ば、めっき付着量が２０ｇ／ｍ2 のとき、Ｍｇ付着量は
０．６ｇ／ｍ2 となる。Example A Zn-Mg alloy plated steel sheet having the components shown in Table 1 was prepared by using an unannealed cold rolled steel sheet having a sheet thickness of 0.5 mm and a sheet width of 700 mm as a plating original plate by the vapor deposition plating apparatus shown in FIG. did. The amount of plating applied is 20 ~ per side
50 g / m 2 and Mg concentration were set to 3% by weight. For example, when the coating weight is 20 g / m 2 , the Mg coating weight is 0.6 g / m 2 .
【００１８】 [0018]
【００１９】冷却条件を種々変更して製造したＺｎ−Ｍ
ｇ合金めっき鋼板について、めっき層の積層構造を電子
顕微鏡（ＳＥＭ）により観察した。積層構造と冷却条件
との関係を調査したところ、両者の間に表２に示す関係
が成立していた。表２において、めっき層の断面が３層
構造（図１）又は５層構造（図２）になっており、下地
鋼とめっき層との界面に厚み０．５μｍを超えるＺｎ−
Ｆｅ合金層が生成していない場合を○，これらの条件の
何れかでも満足していない場合を×として評価した。Zn-M produced by changing various cooling conditions
The laminated structure of the plated layer of the g-alloy-plated steel sheet was observed with an electron microscope (SEM). When the relationship between the laminated structure and the cooling conditions was investigated, the relationship shown in Table 2 was established between them. In Table 2, the cross section of the plating layer has a three-layer structure (Fig. 1) or a five-layer structure (Fig. 2), and Zn- having a thickness of more than 0.5 µm is formed at the interface between the base steel and the plating layer.
The case where the Fe alloy layer was not formed was evaluated as ◯, and the case where any of these conditions was not satisfied was evaluated as x.
【００２０】 [0020]
【００２１】表２に見られるように、蒸着めっき完了直
後の鋼板温度を３７０℃以下，蒸着めっき完了から１０
秒経過した時点の鋼板温度を３４０℃以下，２０秒経過
した時点の鋼板温度を３２０℃以下，４０秒経過した時
点の鋼板温度を３００℃以下にした製造番号１〜１２で
は、何れも正常な３層又は５層構造をもつＺｎ−Ｍｇ合
金めっき層が形成されていた。他方、めっき完了直後の
鋼板温度が３７０℃を超えた製造番号１３〜１５では、
何れも適正な積層構造をもっためっき層が形成されなか
った。製造番号１３では、図４に示すように下地鋼の上
に厚みが１．３μｍにも達するＺｎ−Ｆｅ合金層が生成
しており、このＺｎ−Ｆｅ合金層の上にめっき層の厚み
全体にわたってＭｇが拡散した１層状態のめっき層とな
っていた。製造番号１４，１５では、図５に示すように
何れも下地鋼の上に厚さ０．８μｍのＺｎ−Ｆｅ合金層
が生成していた。また、Ｚｎ−Ｆｅ合金層の上には、１
層状態のＺｎ−Ｍｇ合金層が形成されていた。As shown in Table 2, the steel sheet temperature immediately after the completion of the vapor deposition plating was 370 ° C. or less,
In the production numbers 1 to 12, in which the steel plate temperature after lapse of seconds was 340 ° C or less, the steel plate temperature after 20 seconds was 320 ° C or less, and the steel plate temperature after 40 seconds was 300 ° C or less, all were normal. A Zn-Mg alloy plating layer having a three-layer or five-layer structure was formed. On the other hand, in the production numbers 13 to 15 in which the steel plate temperature immediately after the completion of plating exceeded 370 ° C.,
In neither case, a plating layer having a proper laminated structure was formed. In Production No. 13, a Zn—Fe alloy layer having a thickness of 1.3 μm is formed on the base steel as shown in FIG. 4, and the Zn—Fe alloy layer is formed on the Zn—Fe alloy layer over the entire thickness of the plating layer. It was a single-layer plated layer in which Mg was diffused. In Production Nos. 14 and 15, as shown in FIG. 5, the Zn—Fe alloy layer having a thickness of 0.8 μm was formed on the base steel. Moreover, 1 is formed on the Zn-Fe alloy layer.
A layered Zn-Mg alloy layer was formed.
【００２２】めっき完了から１０秒経過した時点の鋼板
温度が３４０℃を超える製造番号１６，２０秒経過した
時点の鋼板温度が３２０℃を超える製造番号１７，１
９，４０秒経過した時点の鋼板温度が３００℃を超える
製造番号１８では、めっき層断面において、図６に示す
ようにＭｇが固溶したＺｎ層と、ＺｎとＭｇの金属間化
合物層が粒状に混在した１層状態になっており、３層又
は５層の積層構造をもっていなかった。以上の結果か
ら、３層構造（図１）又は５層構造（図２）の積層構造
をもつＺｎ−Ｍｇ合金めっき層を常に安定して形成する
ためには、完了直後の鋼板温度を３７０℃以下，蒸着め
っき完了から１０秒経過した時点の鋼板温度を３４０℃
以下，２０秒経過した時点の鋼板温度を３２０℃以下，
４０秒経過した時点の鋼板温度を３００℃以下にする必
要性があることが確認された。このようにして３層構造
（図１）又は５層構造（図２）の積層構造をもつＺｎ−
Ｍｇ合金めっき層は、本来のＺｎ〜Ｍｇ合金めっきの特
性を十分に発揮し、以下に説明するように耐食性，塗装
密着性，加工性，溶接性等の諸特性が総合的に優れたも
のとなる。Production number 16 when the steel sheet temperature exceeds 340 ° C. 10 seconds after plating is completed, Production number 17 that the steel sheet temperature exceeds 320 ° C. when 20 seconds has elapsed
In Production No. 18 in which the steel sheet temperature exceeds 300 ° C. when 9,40 seconds have passed, in the cross section of the plating layer, as shown in FIG. 6, the Zn layer in which Mg was solid-solved and the intermetallic compound layer of Zn and Mg were granular. In the state of 1 layer mixed with the above, it did not have a laminated structure of 3 layers or 5 layers. From the above results, in order to always stably form the Zn-Mg alloy plating layer having the laminated structure of the three-layer structure (FIG. 1) or the five-layer structure (FIG. 2), the steel plate temperature immediately after completion is 370 ° C. Below, the temperature of the steel sheet at the time of 10 seconds from the completion of vapor deposition plating was 340 ° C.
Below, the temperature of the steel sheet at the time of 20 seconds elapsed is 320 ° C. or less,
It was confirmed that it was necessary to keep the temperature of the steel sheet at 300 seconds or less after 40 seconds had passed. In this way, Zn-- having a three-layer structure (FIG. 1) or a five-layer structure (FIG. 2) is laminated.
The Mg alloy plating layer fully exhibits the original characteristics of Zn to Mg alloy plating, and as described below, it is comprehensively excellent in various characteristics such as corrosion resistance, coating adhesion, workability, and weldability. Become.
【００２３】塗膜二次密着性，黒変色性，スポット溶接
性 表２の条件で製造したＺｎ−Ｍｇ合金めっき鋼板から試
験片を切り出し、塗膜二次密着性，黒変色性及びスポッ
ト溶接性を調査した。各試験片は、それぞれの試験前に
０．５％ＨＣｌ水溶液で酸洗し、表面のＭｇ濃化層を除
去して試験に供した。塗膜二次密着性試験では、前処理
として燐酸塩処理を施した後、アクリル系の電着塗装を
塗膜厚み２０μｍで施した。塗装した試験片を５０℃の
蒸留水中に１０００時間浸漬した後、カッターナイフに
より１ｍｍ間隔で碁盤目状の疵をつけ、テープ剥離試験
を行った。そして、テープに付着して試験片表面から剥
離しためっき層をカウントし、剥離面積が５％以下のも
のを○，５〜５０％のものを△，５０％を超えるものを
×として評価した。黒変色性は、温度５０℃及び相対湿
度６０％の促進試験機の中に試験片を１０００時間放置
し、試験前後の明度差ΔＬ* によって評価した。スポッ
ト溶接性は、単相交流型の溶接機に先端径４．５ｍｍの
ＣＦ型Ｃｕ−１％Ｃｒ電極を装着し、連続溶接が可能な
打点数によって評価した。 Secondary adhesion of coating film, black discoloration, spot welding
The test pieces were cut out from the Zn-Mg alloy-plated steel sheet produced under the conditions of Table 2 and the secondary adhesion of the coating film, black discoloration and spot weldability were investigated. Prior to each test, each test piece was pickled with a 0.5% HCl aqueous solution to remove the Mg concentrated layer on the surface and subjected to the test. In the coating film secondary adhesion test, after performing a phosphate treatment as a pretreatment, an acrylic electrodeposition coating was applied with a coating film thickness of 20 μm. The coated test piece was dipped in distilled water at 50 ° C. for 1000 hours, and then a checkerboard-like flaw was made at 1 mm intervals with a cutter knife to perform a tape peeling test. Then, the plating layers that adhered to the tape and peeled from the surface of the test piece were counted, and those having a peeled area of 5% or less were evaluated as ◯, 5 to 50% as Δ, and those exceeding 50% were evaluated as x. The black discoloration property was evaluated by the brightness difference ΔL * before and after the test, in which the test piece was left for 1000 hours in an accelerated tester at a temperature of 50 ° C. and a relative humidity of 60%. The spot weldability was evaluated by mounting a CF type Cu-1% Cr electrode having a tip diameter of 4.5 mm on a single-phase AC welding machine and evaluating the number of dots capable of continuous welding.
【００２４】 [0024]
【００２５】調査結果を示す表３で実施例として掲げた
二つの試験片は、Ｚｎ−Ｍｇ合金めっき鋼板として適正
な３層又は５層の適正な断面構造をもつものである。比
較例として掲げた試験片は、何れもＭｇを固溶したＺｎ
層とＺｎ−Ｍｇ金属間化合物層が粒状に混在した１層状
態になっており、Ｚｎ−Ｍｇ合金めっき鋼板の断面構成
としては不適正なものである。試験の結果、塗膜の二次
密着性，黒変色性及びスポット溶接性の何れについて
も、適正な断面構造をもつ実施例の試験片が優れた特性
を示した。これは、適正な断面構造をもつ試験片がめっ
き層の最表層にＭｇ濃度０．５重量％以下のＺｎ−Ｍｇ
合金層が形成されていることに由来する。これに対し、
比較例の試験片では、めっき層の最表層にＭｇ濃度０．
５重量％以下のＺｎ−Ｍｇ合金層がないため、良好な塗
膜二次密着性が得られず、表面の色も−２０以上の大き
く黒変し、スポット溶接の連続打点寿命も実施例と比較
して半分程度に過ぎなかった。The two test pieces listed as examples in Table 3 showing the investigation results have an appropriate cross-sectional structure of 3 layers or 5 layers suitable as a Zn-Mg alloy plated steel sheet. All the test pieces listed as comparative examples were Zn containing Mg as a solid solution.
The layer and the Zn-Mg intermetallic compound layer are mixed in a granular form to form a single layer, which is not appropriate as the cross-sectional structure of the Zn-Mg alloy plated steel sheet. As a result of the test, the test piece of the example having an appropriate cross-sectional structure exhibited excellent properties with respect to the secondary adhesion of the coating film, the black discoloration property, and the spot weldability. This is because the test piece having an appropriate cross-sectional structure was formed on the outermost surface of the plating layer with a Zn concentration of 0.5% by weight or less.
This is because the alloy layer is formed. In contrast,
In the test piece of the comparative example, the Mg concentration of 0.
Since there is no Zn-Mg alloy layer of 5% by weight or less, good secondary adhesion of the coating film cannot be obtained, the surface color is greatly blackened by -20 or more, and continuous spot welding life of spot welding is the same as that of the example. It was only about half of the comparison.
【００２６】加工性 Ｚｎ−Ｍｇ合金めっき鋼板として、適正な３層又は５層
の断面構造をもつものと、１層構造になった不適性なも
のとで加工性の違いを比較した。各試験片は、それぞれ
の試験前に０．５％ＨＣｌ水溶液で酸洗し、表面のＭｇ
濃化層を除去して試験に供した。加工性試験では、パウ
ダリング発生量で加工性を評価した。パウダリング性
は、高さ４ｍｍ，Ｒ＝０．５ｍｍのビードをつけた金型
に試験片を挾み、金型への加圧力５００ｋｇ及び引抜き
速度２００ｍ／分で金型から試験片を引抜くドロービー
ド法試験で調査した。Workability The difference in workability between Zn-Mg alloy plated steel sheets having an appropriate three-layer or five-layer cross-sectional structure and inadequate one-layer structure was compared. Prior to each test, each test piece was pickled with a 0.5% HCl aqueous solution to remove Mg on the surface.
The concentrated layer was removed and used for the test. In the workability test, workability was evaluated by the amount of powdering generated. As for the powdering property, the test piece is sandwiched in a mold equipped with a bead having a height of 4 mm and R = 0.5 mm, and the test piece is pulled out from the mold at a pressing force of 500 kg and a drawing speed of 200 m / min. It was investigated by the draw bead method test.
【００２７】 [0027]
【００２８】試験結果を示す表４から明らかなように、
比較例の試験片は、何れもパウダリングの発生量が多
く、加工性に劣ったものであった。これは、製造時の冷
却条件が不適正であったため、延性に富む第１層がな
く、またＺｎ−Ｆｅ合金層が厚く成長したことに原因が
ある。これに対し、適正な冷却条件で製造した実施例の
試験片では、第１層と下地鋼との間に薄いＦｅ−Ｚｎ合
金層が観察され、良好な加工性を呈していた。As is clear from Table 4 showing the test results,
The test pieces of the comparative examples all had a large amount of powdering and were inferior in workability. This is because the cooling conditions at the time of manufacture were improper, and thus there was no first layer rich in ductility, and the Zn—Fe alloy layer grew thick. On the other hand, in the test piece of the example manufactured under an appropriate cooling condition, a thin Fe—Zn alloy layer was observed between the first layer and the base steel, and exhibited good workability.
【００２９】[0029]
【発明の効果】以上に説明したように、本発明において
は、蒸着めっき完了直後及び蒸着めっき完了からの経過
時間に応じて鋼板温度を制御することにより、Ｍｇ及び
Ｚｎの拡散を適正に管理し、Ｚｎ−Ｍｇ合金めっき層の
断面構造を常に適正な３層又は５層の積層構造にしてい
る。この３層又は５層の積層構造をもつＺｎ−Ｍｇ合金
めっき鋼板は、本来のＺｎ〜Ｍｇ合金めっきの特性を十
分に発揮し、耐食性，塗装密着性，加工性，溶接性等の
諸特性が総合的に優れた材料として広範な分野で使用さ
れる。As described above, according to the present invention, the diffusion of Mg and Zn is properly controlled by controlling the steel sheet temperature immediately after the completion of vapor deposition plating and according to the elapsed time from the completion of vapor deposition plating. , Zn-Mg alloy plated layer has a cross-sectional structure that is always a proper three-layer or five-layer laminated structure. This Zn-Mg alloy plated steel sheet having a three-layer or five-layer laminated structure fully exhibits the original characteristics of Zn-Mg alloy plating and has various characteristics such as corrosion resistance, coating adhesion, workability, and weldability. It is used in a wide range of fields as a comprehensively superior material.
【図１】 ３層構造をもつＺｎ−Ｍｇ合金めっき層FIG. 1 is a Zn-Mg alloy plating layer having a three-layer structure.
【図２】 ５層構造をもつＺｎ−Ｍｇ合金めっき層FIG. 2 Zn-Mg alloy plating layer having a five-layer structure
【図３】 本発明に従ってＺｎ−Ｍｇ合金めっき鋼板を
製造するラインFIG. 3 is a line for producing a Zn—Mg alloy plated steel sheet according to the present invention.
【図４】 Ｍｇが固溶したＺｎ層及びＺｎ−Ｍｇの金属
間化合物が混粒状で１層となった製造番号１３のＺｎ−
Ｍｇ合金めっき鋼板のめっき層構造FIG. 4 is a Zn-layer of production number 13 in which a Zn layer in which Mg is dissolved and a Zn-Mg intermetallic compound are mixed to form one layer.
Mg alloy plated steel sheet plating layer structure
【図５】 Ｍｇが固溶したＺｎ層及びＺｎ−Ｍｇの金属
間化合物が混粒状で１層となった製造番号１４，１５の
Ｚｎ−Ｍｇ合金めっき鋼板のめっき層構造FIG. 5 is a plating layer structure of Zn-Mg alloy-plated steel sheets of production numbers 14 and 15 in which a Zn layer in which Mg is dissolved and a Zn-Mg intermetallic compound are mixed and granular to form one layer.
【図６】 Ｍｇが固溶したＺｎ層及びＺｎ−Ｍｇの金属
間化合物が混粒状で１層となった製造番号１６〜１９の
Ｚｎ−Ｍｇ合金めっき鋼板のめっき層構造FIG. 6 is a plating layer structure of a Zn-Mg alloy plated steel sheet of production numbers 16 to 19 in which a Mg solid solution Zn layer and a Zn-Mg intermetallic compound are mixed granules to form one layer.
１０：めっき原板 １１：ペイオフリール １５：
めっき鋼帯 １６：巻取りリール ２０：無酸化炉 ２５：還元焼鈍炉 ２６：鋼板温
度制御装置 ３０：真空室 ３１：入側真空シール部 ３２：出
側真空シール部 ３３：第１Ｚｎ蒸着室 ３４：Ｍｇ蒸着室 ３５：
第２Ｚｎ蒸着室 ４０：一次冷却装置 ４５：二次冷却装置 ５１〜
５５：温度計10: plating original plate 11: pay-off reel 15:
Plated steel strip 16: Take-up reel 20: Non-oxidizing furnace 25: Reduction annealing furnace 26: Steel plate temperature control device 30: Vacuum chamber 31: Incoming side vacuum seal part 32: Outgoing side vacuum seal part 33: First Zn vapor deposition chamber 34: Mg deposition chamber 35:
Second Zn vapor deposition chamber 40: Primary cooling device 45: Secondary cooling device 51-
55: Thermometer
───────────────────────────────────────────────────── フロントページの続き (72)発明者 斎藤 実 大阪府堺市石津西町５番地 日新製鋼株式 会社技術研究所内 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Minoru Saito 5th Ishizu Nishimachi, Sakai-shi, Osaka Nisshin Steel Co., Ltd.
Claims (1)
し、Ｚｎ，Ｍｇ，Ｚｎの順に蒸着めっきした後、蒸着め
っき完了直後の鋼板温度が３７０℃以下、蒸着めっき完
了から１０秒後の鋼板温度が３４０℃以下、２０秒後の
鋼板温度が３２０℃以下、４０秒後の鋼板温度が３００
℃以下になる冷却条件下で、めっき後の鋼板を冷却する
ことを特徴とするＺｎ−Ｍｇ合金めっき鋼板の製造方
法。1. A continuously running steel plate is introduced into a vacuum chamber, and Zn, Mg, and Zn are vapor-deposited in this order, and the steel plate temperature immediately after completion of vapor deposition plating is 370 ° C. or lower, and 10 seconds after completion of vapor deposition plating. Steel plate temperature is 340 ° C. or lower, steel plate temperature after 20 seconds is 320 ° C. or lower, steel plate temperature after 40 seconds is 300
A method for producing a Zn-Mg alloy-plated steel sheet, which comprises cooling the steel sheet after plating under cooling conditions of not higher than 0 ° C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25815495A JPH0978229A (en) | 1995-09-11 | 1995-09-11 | Production of zinc-magnesium alloy plated steel sheet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25815495A JPH0978229A (en) | 1995-09-11 | 1995-09-11 | Production of zinc-magnesium alloy plated steel sheet |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0978229A true JPH0978229A (en) | 1997-03-25 |
Family
ID=17316282
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP25815495A Withdrawn JPH0978229A (en) | 1995-09-11 | 1995-09-11 | Production of zinc-magnesium alloy plated steel sheet |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0978229A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009054716A (en) * | 2007-08-24 | 2009-03-12 | Hitachi Metals Ltd | RARE EARTH-BASED PERMANENT MAGNET HAVING Mg-CONTAINING Al COATING ON SURFACE THEREOF, AND MANUFACTURING METHOD THEREOF |
| EP2085492A1 (en) | 2007-12-28 | 2009-08-05 | Posco | Zinc alloy coated steel sheet having good sealer adhesion and corrosion resistance and process of manufacturing the same |
| JP2022514409A (en) * | 2018-12-19 | 2022-02-10 | ポスコ | Plated steel material with excellent plating adhesion and corrosion resistance and its manufacturing method |
| WO2023110178A1 (en) * | 2021-12-14 | 2023-06-22 | Thyssenkrupp Steel Europe Ag | Method for producing a flat steel product having cathodic corrosion protection, system for producing a flat steel product provided with cathodic corrosion protection, and use |
-
1995
- 1995-09-11 JP JP25815495A patent/JPH0978229A/en not_active Withdrawn
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009054716A (en) * | 2007-08-24 | 2009-03-12 | Hitachi Metals Ltd | RARE EARTH-BASED PERMANENT MAGNET HAVING Mg-CONTAINING Al COATING ON SURFACE THEREOF, AND MANUFACTURING METHOD THEREOF |
| EP2085492A1 (en) | 2007-12-28 | 2009-08-05 | Posco | Zinc alloy coated steel sheet having good sealer adhesion and corrosion resistance and process of manufacturing the same |
| JP2022514409A (en) * | 2018-12-19 | 2022-02-10 | ポスコ | Plated steel material with excellent plating adhesion and corrosion resistance and its manufacturing method |
| WO2023110178A1 (en) * | 2021-12-14 | 2023-06-22 | Thyssenkrupp Steel Europe Ag | Method for producing a flat steel product having cathodic corrosion protection, system for producing a flat steel product provided with cathodic corrosion protection, and use |
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